(1) Field of the Invention
The present invention pertains to a guide employed on air conveyors of the type that suspend conveyed objects from an intermediate enlargement, for example, conveying plastic bottles by suspending the bottles from their neck rings, where the guide limits the upward movement of the objects thereby preventing the objects from becoming jammed in the conveyor system. More specifically, the present invention pertains to a guide that limits the upward movement of plastic bottles conveyed by a conveyor system preventing the bottles from becoming wedged in the air conveyor and jamming the flow of bottles through the air conveyor while permitting each of the bottles conveyed to swing freely forwardly and rearwardly from their neck rings as the bottles are conveyed through the conveyor.
(2) Description of the Related Art
An air conveyor is useful in the rapid transport of plastic bottles between work stations as, for example, between a blow molding station and a palletizing station. Air conveyors of this type are disclosed in the U.S. patents of Ouellette, U.S. Pat. No. 5,437,521 issued Aug. 1, 1995, and U.S. Pat. No. 5,611,647 issued Mar. 18, 1997, both of which are incorporated herein by reference.
FIG. 1 shows an end elevation view of a typical air conveyor. The conveyor includes a conveyor channel 12 having a generally inverted U-shaped configuration with a top wall 14 and laterally spaced sidewalls 16, 18. Together, the channel top wall 14 and sidewalls 16, 18 give the conveyor channel its general, inverted U-shaped configuration surrounding an interior volume 22 of a conveyor channel. The sidewalls 16, 18 of the conveyor channel have lower sections 24, 26, respectively, connected to the upper sidewalls by threaded fasteners 28, 32. The two lower sections of the sidewalls 24, 26 have pluralities of air duct outlets 34, 36 that extend through the conveyor channel sidewalls. The configurations of the air duct outlets 34, 36 direct jets of air ejected from the outlets to strike bottle containers conveyed by the air conveyor in the area of the shoulder of the containers, thereby forcing the containers to travel downstream along the length of the air conveyor.
Each of the air duct outlets 34, 36 is fed with pressurized air conveyed through air ducts 38, 42 that extend through the upper portions of the conveyor channel sidewalls 16, 18. These air ducts 38, 42 extend from the top surface of the conveyor channel top wall 14 completely through the channel sidewalls 16, 18 to the sidewall lower sections 24, 26.
Branch portions 44, 46 of the air ducts extend partially through the conveyor channel sidewalls 16, 18 and exit the sidewalls into the conveyor channel interior volume through vacuum port openings 48, 52. The air duct branch portions 44, 46 communicate with the air duct outlets 34, 36. As pressurized air passes through the air ducts 38, 42 in the sidewalls and then through the air duct outlets 34, 36, a venturi effect is created in the air duct outlets 34, 36 that draws a suction through the branch portions 44, 46 and vacuum port openings 48, 52. This suction reduces the air pressure in the upper portion of the channel interior volume 22.
The channel interior volume 22 is divided into an upper portion and a lower portion by a pair of laterally spaced, longitudinally extending flanges 54, 56. The pair of flanges extend from the pair of channel sidewalls 16, 18 into the channel interior volume 22 and mutually oppose each other defining a slot 58 therebetween. The left side flange 54 as viewed in FIG. 1 is held between projecting portions of the conveyor channel sidewall 16 and the sidewall lower section 24 on the left side of the channel by a plurality of set screws 62, only one of which is shown in FIG. 1. The flange 56 on the right side of the channel is held between a projecting portion of the conveyor channel sidewall 18 and the sidewall lower section 26 by a plurality of set screws 62, only one of which is visible in FIG. 1. By loosening the set screw 62, the flanges 54, 56 can be removed from the conveyor channel entirely and replaced with new flanges, or can be adjustably positioned laterally toward and away from each other to adjust the lateral width of the slot 58. In bottle conveyors, the lateral width of the slot 58 is adjusted to be sufficiently large to receive the neck of a bottle container therein with the annular rim or neck ring of the bottle supported on top surface margins 64, 66 of the flanges with the tapered shoulder and body of the bottle suspended below the pair of flanges.
An air plenum 68 extends longitudinally along the top wall 14 of the conveyor channel. The plenum 68 is comprised of a pair of sidewalls 72, 74 and a top wall 76 that surround an interior 78 of the plenum. As shown in FIG. 1, a connecting plate 82 is positioned just above the conveyor channel top wall 14 and is connected to the opposed air plenum sidewall 72, 74. The connecting plate 82 is employed in connecting together adjacent lengths of the conveyor channel end-to-end and is only present at the connection between the two lengths of conveyor channel. It does not extend the entire longitudinal length of the conveyor channel as does the channel top wall 14 which acts as the bottom wall of the air plenum 68. As shown in FIG. 1, the connecting plate 82 is connected to the top wall 14 of the conveyor channel by a threaded fastener 84 and is also connected to the opposed air plenum sidewalls 72, 74 by a pair of threaded fasteners 86. When the connecting plate 82 overlays the air ducts 38, 42 of the conveyor channel, a pair of holes 88, 92 are provided in the connecting plate 82 in order to maintain communication of the pressurized air in the air plenum 68 with the conveyor channel air ducts 38, 42.
In operation of the conveyor channel 12, air is supplied at a regulated pressure to the plenum interior volume 78 by a conventional blower (not shown). The air pressure supplied to the plenum interior is directed through the holes 88, 92 of the connecting plate 82 where present, and through the sidewall air ducts 38, 42 and is ejected through the air duct outlets 34, 36. The jets of air ejected from the air duct outlets 34, 36 cause the object or bottle suspended in the slot 58 to be conveyed along the slot in a desired downstream direction. The venturi effect created in the air ducts draws a vacuum pressure through the vacuum port openings 48, 52 which open into the conveyor channel interior volume above the pair of flanges 54, 56. The vacuum created in the channel above the flanges exerts an upwardly pulling force on the upper portion of the bottle container suspended from its annular ring in the slot and thereby reduces the friction drag of the bottle annular ring supported on the top surface margins 64, 66 of the flanges.
As stated earlier, air conveyors of the type just described and other similar air conveyors are employed to transport empty plastic bottles, although it is conceivable they could be configured to transport other objects having an intermediate enlargement such as the neck ring of the bottles, with an upper portion of the object such as the bottle neck positioned above the intermediate enlargement and a lower portion of the object such as the bottle shoulder and body positioned below the intermediate enlargement. The ability to adjust the position of the conveyor flanges 54, 56, or to replace flanges with those of different sizes, enables air conveyors of the type described to transport a variety of bottles having different shapes and configurations. For example, the air conveyors are employed in transporting plastic bottles having a 28 millimeter diameter neck opening at their tops such as those provided on conventional one liter quart bottles, as well as transporting bottles having a 38 millimeter diameter neck opening at their tops such as that employed on the "wide mouth" type bottles.
In transporting plastic bottles by air conveyors, it has been found that it is desirable to give the upper portion or neck of the bottle a longitudinally downstream angled orientation as the bottle is transported along the longitudinal length of a conveyor. With this orientation of the bottle relative to the conveyor, the bottles have a lesser tendency for jamming in the conveyor slot. In order for the bottle to obtain this orientation when being transported along the conveyor, the bottle must be free to swing forwardly and rearwardly from the annular neck ring or intermediate enlargement supporting the bottle on the conveyor flanges. However, in providing clearance for the swinging movement of the bottles on the flanges of the air conveyor, the bottles are capable of moving vertically upward relative to the air conveyor, resulting in their annular neck rings being lifted from supporting engagement with the top surface margins of the conveyor flanges. It has been observed that, when a series of bottles are stopped along an air conveyor for whatever reason, when a moving bottle contacts the stopped bottles, it will have a tendency to move upwardly relative to the air conveyor on impact of the bottles together. It has also been observed at times that the upward movement of a bottle at impact with stationary bottles will result in the tapered shoulders of the bottle below the neck ring becoming wedged between the opposed edges of the conveyor flanges, jamming the bottle between the flanges. It has also been observed that plastic bottles exhibit a polarity attraction to each other shortly after their being blow molded. When a conveyed bottle strikes a stationary bottle on an air conveyor shortly after the bottles have been blow molded, not only will the bottle at times move upwardly resulting in its tapered shoulders becoming wedged and jammed between the conveyor flanges, the polarity attraction between adjacent bottles will contribute to holding the jammed bottle in its position wedged between the opposed conveyor flanges. What is needed to overcome this problem is an improvement to the air conveyor that limits the upward movement of conveyed bottles relative to the conveyor slot while still permitting the free forwardly and rearwardly swinging of the bottles suspended from their annular neck rings on the flanges of the conveyor.